Blockchain?

Distributed ledgers, decentralization, smart contracts, and the other f*kng jargon about blockchain. What is the underlying principals of this tech? Is the real implementation truly exist beside that so many opportunistic ICO? Is the smart contracts capable of securing transactions for a large scale? Isn’t the ownership of bitcoin already becoming a centralized power which is irony? Are there any real business model other than a new coin?

It looks every year in tech world is always about jargon, not yet a solution.